1. Field of the Invention
The present invention relates to a method for manufacturing a liquid discharge head for discharging liquids and more particularly, to a method for forming minute flow passageways at a high efficiency, which are provided in a liquid discharge head employed for an inkjet recording system.
2. Description of the Related Art
An example system that employs a liquid discharge head is an inkjet recording system that discharges ink to recording media to perform recording.
An inkjet recording head, adapted for use in an inkjet recording system, is generally provided with ink discharge ports and ink flow passageways, and energy generating elements, positioned along the ink flow passageways to generate energy necessary for discharging ink through the ink discharge ports, via the ink flow passageways. The ink flow passageways of the inkjet recording head conventionally are formed by using the well known manufacturing methods as set forth below.
According to the manufacturing method disclosed in U.S. Pat. No. 5,478,606, first, a pattern that serves as an ink flow passageway forming die is provided, using a soluble resin, on a substrate whereon energy generating elements have been formed, and then, a coating resin layer, which is used to form the ink flow passageway walls, is deposited on the ink flow passageway die-pattern. Subsequently, photolithography is used to form orifices in the energy generating elements, and then, the ink flow passageway forming-die pattern is melted, to cure the coating resin layer used to define the ink flow passageway walls.
A high processing speed and image quality are demanded for a recent inkjet printer, and accordingly, micromachining is employed for formation of ink flow passageways in an inkjet recording head.
According to the method for forming ink flow passageways using die-patterns, as described in the specification of U.S. Patent Application Publication No. US-2004-0131957, the three-dimensional shape of the minute structure used for ink flow passageways is optimized to increase the ink refilling speed. According to this method, first, a first positive type photosensitive material layer, which is to be exposed to light in a first wavelength range in a bridged state, is deposited on a substrate on which energy generating elements have been formed. Then, the first positive type photosensitive material layer is heated to obtain a bridged positive type photosensitive layer (a lower layer). Following this, an upper layer, composed of a second positive type photosensitive material, which is to be exposed to light in a second wavelength range different from that used for the first wavelength range, is deposited on the lower layer, and as a result, a two-layer structure is obtained. Thereafter, a predetermined portion of the upper layer of the two-layer structure is subjected to radiation of light in the second wavelength range for achieving a developing process. Thus, only the irradiated portion of the upper layer is removed, and a predetermined pattern is formed on the upper layer. Further, a predetermined area of the lower layer, exposed during the pattern formation process employed for the upper layer, is irradiated with light in the first wavelength range to conduct the developing process. In this manner, a predetermined pattern is formed on the lower layer. Through the above-described processing, a pattern can be formed, which can serve as a flow passageway forming die having the optimized three-dimensional shape.
However, when the inkjet recording head manufacturing method described in U.S. Patent Application Publication No. US-2004-0131957 is used, two different wavelengths must be employed for the exposure steps and therefore, the number of processing steps will probably be increased.